It's certainly the case that a lot of very rich people want their taxes low, and they provide Norquist and a few other powerful conservatives the means to enforce strict discipline among elected officials to keep them that way. Whatever their views about taxes, Republicans don't want to be primaried, and if they don't follow the rules, they know their political lives will be on the line.
That's the mechanism.
But there's something unique about Norquist's rules that distinguish him from the Club for Growth or other powerful conservative anti-tax voices: Unlike the rest of them, he has the pledge.
The pledge can be read leniently or strictly or somewhere in between, but it basically says Republicans can't vote to increase net tax revenue. For much of this year, and the year before, and most of the past decade, the meaning was plain. Pretty much any legislation that resulted in tax increases was verboten. But if you apply that same strict standard to the current historical moment, the pledge, unlike other anti-tax diktats, is actually harmful to conservative goals.
Harmful because, by law, taxes will go up a lot unless Congress does...something. That is the horn of the dilemma. Inaction leads to the expiration of all of the Bush tax cuts. Cutting a deal with Democrats -- perhaps even an elusive and ill-defined grand bargain that raises revenues above their current levels -- could yield a smaller overall tax increase than the one scheduled for the beginning of the year. So Republicans are faced with an uncomfortable choice: they're damned if they don't, damned a little less if they do.
That's the reason to pay attention to the exquisite tension between Norquist and rank and file Republicans. As long as Norquist insists that his pledge is to be interpreted strictly, Republicans can't compromise and provide Obama a penny of new federal revenues without violating it. And if Norquist still has sway, and Republicans don't cast him aside, that means taxes will go way, way up next year, and the GOP will have missed its opportunity to minimize damage to the cause.
He's a very real part of the reason the decision-making process in the GOP has become irrational. And unless he recognizes the dilemma Republicans face, and retreats to some loose interpretation of the pledge (at great cost to his influence), or Republicans write him off en masse (at greater cost to his influence) then these fiscal negotiations are going nowhere.
It's twilight for anti-tax absolutists, and Grover is their patron saint.